NEW DELHI — As a thick, ghostly haze shrouded India's capital city, Juhi Dhaul and her family packed their bags and planned to leave town.

"My kids have been sitting in one room with three air purifiers on since Wednesday," she said. "They're virtually under house arrest."

New Delhi's air quality consistently ranks among the worst in the world, but the city's air pollution last week registered 10 times worse than the air in Beijing, which is notorious for its smog. Residents complain of burning eyes and itchy throats, and doctors said chest infections and respiratory illnesses have surged.

Authorities ordered 6,000 schools to close, trucks except those carrying essential supplies have been banned from entering the city for a week, and construction projects have been temporarily stopped.

Dhaul and her family escape to other cities around the country each winter, when pollution levels peak. But for the past few years, Dhaul says, things have been so bad that they may relocate permanently.

"Our kids' lungs are aging faster than they are," she said. "My 6-year-old is very allergic, so when pollution levels go up, she breaks out in rashes. And she has a never-ending dry cough."

Children often feel the physical effects of the toxic air acutely; in addition to closed schools, sports and outdoor play are being discouraged in the toxic air. Many sit cooped up at home, some with little more than a cloth wrapped around their faces to protect against the smoky air.

Smog envelops buildings on the outskirts of New Delhi in November 2014. Air quality worsens in India each winter. (ROBERTO SCHMIDT/AFP/Getty Images)

"Every winter, the weather becomes hostile," said Anumita Roychowdhury, executive director at the Center for Science and Environment in New Delhi. "Around this time of year, the air is cooler and the wind disappears almost entirely from the city. What you see is combination of local pollution plus episodic pollution, from winds from surrounding regions where farmers burn crop stubble in this season."

In some parts of Delhi, air-quality readings were 40 times the World Health Organization's recommended safe level. Airfare spiked as supply dipped in low-visibility conditions; trains were delayed and bus companies reported that people were canceling tickets out of fear of highway accidents.

In a less affluent quarter of the city, Baburam Durbedy's grandson hasn't been eating. "His temperature is up and he keeps getting out of breath," Durbedy said, who wiped his own irritated eyes as he spoke.

Durbedy earns just enough to survive, working as a security guard in the city. Buying high-end air purifiers is not an option, nor is expensive medical care. The family of five has two thin gas masks to share. "We just rub Vicks on his chest," he said, referring to the medicated vapor rub.

"We've seen around a 30 to 35 percent increase of patients in the past couple of days," said Anupam Sibal, group medical director and senior pediatrician at Apollo Hospitals. "It wasn't like this five years ago. Children with respiratory problems are finding their issues are exacerbated. It affects everyone."

Delhi's chief minister described the city as a "gas chamber," and the government introduced a slew of emergency measures, including shutting down a coal-fired power plant and polluting brick kilns, and introducing an "odd-even" program, in which cars can be driven only on alternating days of the week depending on their license plate numbers in an effort to curb traffic.

At one school, the annual sports day ceremony was canceled. "Everyone is really disappointed," said 17-year old Sehej Arora, who helped organize the event. "It's one thing our entire school looks forward to together. We were upset at first, but within 10 minutes of being outside, you can feel the air. My throat itches."

Others scrambled to find work outside the city. Aditya Khanna, who splits his time between England and India, relocated his family to London a month ago partly because of how bad the air is.

"Obviously you don't want to see your children sick all the time, you don't want to be constantly pumping antibiotics into them," he said. "And it's not fun. The kids don't go out to play because you're constantly concerned. It was very clear to me that I was not going to expose my kids to it on a long-term basis."

A woman drives a scooter through the morning fog to drop off a child to school near New Delhi on Thursday. Some people canceled bus trips because the heavily polluted air made them fear highway accidents. (R S Iyer/AP)